DDC-2374: [GH-634] [WIP] Value objects

[doctrinebot]

Jira issue originally created by user @beberlei:

This issue is created automatically through a Github pull request on behalf of beberlei:

Url: #634

Message:

This pull request takes a different approach than GH-265 to implement ValueObjects. Instead of changing most of the code in every layer, we just inline embedded object class metadata into an entities metadata and then use a reflection proxy that looks like "ReflectionProperty" to do the rewiring.

The idea is inspired from Symfony Forms 'property_path' option, where you can write and read values to different parts of an object graph.

This is a WIP, there have been no further tests made about the consequences of this approach. The implementation is up for discussion.

[doctrinebot]

• relates to DDC-93: It would be nice if we could have support for ValueObjects

[doctrinebot]

Comment created by @doctrinebot:

A related Github Pull-Request [GH-634] was closed:
#634

[doctrinebot]

Issue was closed with resolution "Invalid"

[doctrinebot]

Comment created by @beberlei:

This PR was superseded.

[doctrinebot]

Comment created by @doctrinebot:

A related Github Pull-Request [GH-634] was assigned:
doctrine/dbal#634